The original concept of Winter sowing uses see through milk cartons and large plastic drinks bottles and is a great way to occupy yourself through the cold dark Winter months when there’s not much that can be done at the allotment.
Traditionally in the United States and Canada these types of mini greenhouses are made by cutting the carton halfway round leaving about 2cm as a hinge for the lid, make holes in the bottom for drainage, discarding the screw top to allow rain/snow in and use duck tape to seal the cut all the way round.
But because I find this method too much work you can make a mini greenhouse out of a cheap tote/storage box that can be reused for years and sow seedlings into cell trays for planting straight out into your allotment or garden when they’ve had time to develop and grow.
Preparing the storage box in 3 easy steps
For this you’ll need:
- a drill
- a small drill bit
- a clear storage box with a snap shut lid that is tall enough to allow seedlings plenty of room to grow
Start by drilling holes into the bottom of the box spacing the holes approximately 2 inches apart.
Make sure that you do not apply too much force to get the drill through the plastic especially in cold weather as it may cause the plastic to crack. Go gently.
These holes will allow rain water and snow melt into the mini greenhouse and provide your seedlings with natural water helping them to get off to the best start possible.
Next drill holes into the lid but this time drill them 4 inches apart because you do not need as many holes in the lid for drainage.
All that lovely fresh rain water could overpower your seedlings so making holes in the lid will allow the moisture to drain away and prevent drowning and rot.
Drill one hole in the end of the box about halfway up the side to allow good airflow through the mini greenhouse to help prevent the build up of mould.
The box I used already had small holes by the handles on each side so I skipped this step.
Sowing seeds for a mini greenhouse in Winter
The planting plan takes into account the best times of year in a zone 8 climate to sow seeds including during the Winter. The rule of thumb to follow is to only sow seeds from plants that are cold hardy to increase germination rates.
Below is multi sown coriander two and three seeds to a cell ready for a very light topping of compost, some water and then the mini greenhouse.
You can try you hand at spinach, onions, calabrese, salad mix – virtually any cold hardy plant seeds that will tolerate a cold start to their lives.
Once you’ve sown your seeds simply place them onto the lid and place the box on top making sure to snap it shut. Place it in the sunniest place you can find and then simply leave it until your seedlings have morphed into small plants, ready for potting on or straight into your allotment or garden.
Top tip: always assume that the lid will fall off so when transporting your new mini greenhouse, make sure you have a good hold of it underneath.
Making a mini greenhouse: a video guide
If like me you are a visual learner then you’ll appreciate the video guide I used to make this mini greenhouse.
My thanks goes to Will from the Garden Dragon YouTube channel for this most excellent guide.